Passive stabilizers for tankers and the like



Dec. 12, 1967 s. B. FIELD ETAL 3,357,391

PASSIVE STABILIZERS FOR TANKIJRS AND THE LIKE S Sheets-Sheet 1 OriginalFiled April 5, 1965 S s m m m m N .u 9 e d g .m w h F a "W m v+ V M F A1, m Q v\ M m D o .QE w H a m ,M v MN m i w S Q QN V\ n N NW T0000 h3'1; 1 I4 k. m Q 9 BE Dec. 12, 1967 s. B. FIELD ETAL 3,357,391

PASSIVE STABILIZERS FOR TANKERS AND THE LIKE Original Filed April 5,1965 5 Sheets-Sheet z:

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W III J IIIHI I ll I ll I ll/Ill ill il I I L 2% INVENTORS She/don 5.Field Thomas F. Bridges BY v aw J na ATTORNEYS United States Patent3,357,391 PASSEVE STABILIZERS FGR TANKERS AND THE LIKE Sheldon 13.Field, Floral Park, and Thomas F. Bridges, Port Washington, N.Y.,assignors to John J. McMullen Associates, 1118., New York, N.Y., acorporation of New York Continuation of application Ser. No. 445,514,Apr. 5, 1965. This application May 12, 1967, Ser. No. 638,159 6 Claims.(Cl. 114-425) ABSTRACT OF THE DISCLOSURE A passive stabilization systemfor a tanker having a longitudinal structural bulkhead with horizontalstiifeners secured thereto and spaced at vertical intervals to insurethe structural integrity of the bulkhead. Enlarged openings of generallysquare configuration with rounded corners are cut in the bulkhead inhorizontally and vertically aligned zones and each large opening has avertical dimension greater than the vertical spacing between the nearesthorizontal sti feners so that the total open area of the large openingsin the bulkhead is less than if the openings were small cuts arrangedonly between the stiffeners for the case where the same amount of tankliquid passage damping is provided by the bulkhead.

This application is a continuation of application No. 445,514, filedApr. 5, 1965, and now abandoned.

The present invention relates to improvements in ms sive stabilizationsystems for liquid cargo tankers and the like.

t is generally known that the sizes of newly designed liquid cargotankers are now over 100,000 dead weight tons and due to this increasedcargo carrying capability, the structural requirements for vessels ofthis type are becoming more exacting. Consequently, the presentinvention is drawn to improvements in the incorporation of passivestabilizers in vessels of this type.

It is a primary purpose of the present invention to provide a fiume typepassive stabilization system in cargo tankers, said system comprisingthe existing structural elements of the tanker; it is within the scopeof this primary object to provide openings within the longitudinalbulkheads of the tanker, said openings being of such nature and designso as to detract as little as possible from the supporting function ofthe structural bulkhead involved and, at the same time, enablesufiicient liquid transfer therethrough so that a suitable stabilizingmoment is imparted to the vessel.

It is another object of the present invention to incorporate openings inthe longitudinal bulkheads of a liquid cargo tanker to enable the sameto function as a nozzle arrangement between the wing tanks andinterconnecting compartment of a passive stabilization system, saidopenin s being of such dimension that the openings are greator than thedistance between the stiffeners mounted on said bulkhead.

It is another and further object of the present invention to provide airholes on the bulkheads with openings of the type described to enable anunimpeded passage of air between the respective compartments of thepassive stabilization system.

Other and further objects of the present invention will become apparentwith the following detailed description when taken in view of theappended drawings in which:

FIG. 1 illustrates a liquid cargo vessel having a portion of its hullshown in section;

FIG. 2 is a horizontal section taken along line 2-2 of FIG. 1;

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FIG. 3 is a vertical section taken along line 33 of FIG. 2; and

FIG. 4 is a vertical section taken along line 44 of FIG. 2.

Stated briefly, the present invention comprises an improvement overknown passive stabilization systems for liquid cargo tankers and thelike which have a plurality of openings in the longitudinal bulkheadsthereof which are aligned and positioned between two transverse oiltightbulkheads. The improvements according to the present invention are drawnto providing the longitudinal bulkheads with large openings of suchshape and dimension as to extend more than the distance between twoparallel stiifeners mounted on the respective bulkhead.

Referring to the figures in detail, there is shown a liquid cargo tankergenerally indicated as 10 having a plurality of transverse oil-tightbulkheads 12 spaced along the longitudinal axis of the vessel. Extendingsubstantially throughout the longitudinal dimension of the vessel is oneor more longitudinal bulkheads 14 which is also oiltight except as heredescribed below. The vessel of the present example has two longitudinalbulkheads.

At least one of the compartments 16 functions as a passive stabilizationsystem, and said compartment 16 is defined by the bottom and top of thehull together with the sides of the hull and transverse bulkheads 12.Bulkheads 14 divide compartment 16 into two outer wing tanks and acenter connecting tank. The portions of the longitudinal bulkheads 14within compartment 16 are provided with a plurality of large openings 20and 22 located across the mid-section of said longitudinal bulkheads 14,to enable communication between each wing tank and the center tank.Smaller openings 24 are also provided along the top of the longitudinalbulkheads to enable unimpeded transfer of air therethrough in responseto the movement of liquid through the larger openings 20 and 22.

A number of web plates 30 having large openings therein are spacedlongitudinally of each other and are mounted transversely with respectto the vessel. These web plates 39 can be of any conventional type andtheir normal function is to provide additional transverse reinforcementto the vessel. As can readily be understood, these web plates alsofunction to some extent as wash plates to prevent wild, uncontrolledmovement of liquid within the compartments.

As better seen in FIGS. 3 and 4, a plurality of horizontally extending Tstiffeners 26 are mounted on the longitudinal bulkheads to providelateral support and stability to the bulkheads in anticipation of largelateral forces exerted by the liquid cargo within the tanks. The Tstiffeners positioned closer to the bottom have an increasing lateraldimension due to the anticipated increased pressure exerted thereat bythe liquid cargo. The stiffeners run throughout the length of thelongitudinal bulkheads in the conventional manner.

Referring now to FIG. 4-, it can be seen that openings 2!) are ofrelatively large dimension and are preferably of square configurationbut have rounded edges because of expected stress fields within thestructural longitudinal bulkhead 14. Openings 20 are of such dimensionso as to extend more than the distance between the horizontal stilieners26 mounted on bulkheads 14. It is preferable but not absolutelynecessary that the stiffeners do not extend across the openings 20.

Outer openings 22 are also of large dimension but are somewhat smallerthan openings 20 also because of the anticipated stress field withinbulkheads 14. In this way, the large openings 20 and 22 enablesuflicient liquid transfer thcrethrough in response to the roll of thevessel, but, at the same time, do not detract from the structural,supporting function of bulkhead 14. Moreover,

with this arrangement of openings 20 and 22, fewer cuts need be madeduring manufacture or installation of the with a set of openings beingpositioned between trans- I verse web plates 30.

In operation, the tanker and compartment 16 are filled to full loadcondition with the liquid cargo to be transported. Alternatively, thevessel and compartment 16 can be filled with ballast to approximatelythe level indicated in FIG. 3. In the event the vessel experiencesforces from without tending to roll the same, the liquid cargo transfersthrough openings 20 and '22 in response to the roll and more liquidtends to accumulate at the lower side of the vessel than at the upperside of the vessel. With this greater accumulation of liquid at thelower side of the vessel, the next portion of the roll cycle of thevessel is impeded due to the stabilizing moment imparted to the ship. Asthe vessel continues to roll, the liquid within tank 16 transfersthrough the openings 20 and 22 to the opposite side of the vessel, whereagain a stabilizing moment is imparted to the vessel. The air withintank 16 transfers unimpeded through small openings 20 at the top of thelongitudinal bulkheads in response to the liquid volume movement withthe respective compartments of tank 16. The vessel is stabilized in thismanner as long as the vessel continues to roll.

It should be understood that other and further modifications can be madeto the disclosure without departing 'from the spirit and scope of thepresent invention.

What is claimed is:

1. In a tanker-like vessel, a stabilization system com prising first andsecond oil-tight transverse bulkheads extending across the hull of theVessel and extending vertically throughout the height of the hull, saidtransverse bulkheads defining with said vessel an elongated, enclosedcontainer arranged across said vessel, at least one longitudinalbulkhead extending through said container and extending verticallythroughout the height of the hull, a plurality of stiffening memberssecured along the longitudinal bulkhead within the container andarranged horizontally at vertically spaced positions so as to increasesuitably the bending modulus of the bulkhead suitably to withstandpredetermined loads, the portion of the bulkhead within the containerdefining large openings therein; and a body of liquid partially fillingsaid container and having a liquid level above the lowest limit of saidopenings, whereby a portion of the liquid transfers through the openingsin response to the roll of the vessel, said longitudinal bulkheaddefining additional openings near the top thereof to enable an unimpededpassage of air therethrough, said large openings being generally squarewith rounded edges and being vertically and horizontally aligned inzones along the longitudinal bulkhead, the vertical dimension of eachlarge opening being greater than the vertical spacing between saidhorizontal stiffening members at generally the same vertical location onsaid longitudinal bulkhead, and some of said stiffening members runningalong the solid parts of the bulkhead above, and below the verticallyspaced large openings.

2. A stabilization system as set forth in claim 1 wherein a group ofsaid large openings are of a first size and a group of said largeopenings are of a second smaller size, wherein the openings of saidfirst size are vertically aligned in sets spaced longitudinally of eachother and the openings of said smaller size are vertically aligned insets near the outer longitudinal limits of the bulkhead within saidelongated container.

3. A stabilization system as set forth in claim 1 wherein the stiffeningmembers which are on the same vertical level as the openings have endswhich terminate substantially at the periphery of said large openings sothat the openings are generally unobstructed.

4. A stabilization system as set forth in claim 3 wherein said containerfurther comprises web member-s mounted in said container and extendingthroughout the height of the hull, and wherein each web member ismounted transversely to the vessel between sets of vertically alignedopenings in thelongitudinal bulkheads.

5. A stabilization system as set forth in claim 1 wherein said largeopenings have an upper limit below the liquid level full liquid loadcondition of the container.

6. A stabilization as set forth in claim 3 wherein those stiffeningmembers not on the same vertical level as an enlarged opening extendcontinuously along the solid parts of said longitudinal bulkhead withinthe container.

References Cited UNITED STATES PATENTS 1/1965 Field l14-l25 7/1966Hilliard 114-125

1. IN A TANKER-LIKE VESSEL A STABILIZATION SYSTEM COMPRISING FIRST AND SECOND OIL-TIGHT TRANSVERSE BULKHEADS EXTENDING ACROSS THE HULL OF THE VESSEL AND EXTENDING VERTI CALLY THROUGHOUT THE HEIGHT OF THE HULL, SAID TRANSVERSE BULKHEADS DEFINING WITH SAID VESSEL AN ELONGATED, ENCLOSED CONTAINER ARRANGED ACROSS SAID VESSEL, AT LEAST ONE LONGITUDINAL BULKHEAD EXTENDING THROUGH SAID CONTAINER AND EXTENDING VERTICALLY TROUGHOUT THE HEIGHT OF THE HULL, A PLURALITY OF STIFFENING MEMBERS SECURED ALONG THE LONGITUDINAL BULKHEAD WITHIN THE CONTAINER AND ARRANGED HORIZONTALLY AT VERTICALLY SPACED POSITIONS SO AS TO INCREASE SUITABLY THE BENDING MODULUS OF THE BULKHEAD SUITABLY TO WITHSTAND PREDETERMINED LOADS, THE PORTION OF THE BULKHEAD WITHIN THE CONTAINER DEFINING LARGE OPENINGS THEREIN; AND A BODY OF LIQUID PARTIALLY FILLING SAID CONTAINER AND 